1. Field of the Invention
This invention relates to an air moving apparatus and in particular to a vacuum cleaner air moving apparatus.
2. Description of the Prior Art
In the conventional vacuum cleaner, an air moving means, such as a fan, is provided within a housing for sucking dirt-laden air from the surface to be cleaned into a dirt-collecting means, such as a collecting bag. It is desirable in such vacuum cleaners to provide high efficiency in the air moving operation so as to provide a suitably powerful suction while yet minimizing the weight, size and cost of the vacuum cleaner.
One conventional air moving means for use in such vacuum cleaners comprises a two-stage fan. While such fans provide improved air moving performance, the are relatively costly.
It is further desirable in such vacuum cleaners to provide a polyhedral housing, such as one having a generally rectangular cross section. On the other hand, the conventional fan has a generally cylindrical configuration and, thus, it has been common to provide a cylindrical housing notwithstanding the general desirability of utilization of a polyhedral housing.
To convert the velocity energy of air delivered by the air moving means into a suction pressure, it has been conventional to utilize diaphragms and the like rearwardly of the air moving means. An example of such a diaphragm is disclosed in U.S. Pat. No. 1,868,659 of Axel O. Engberg et al. The diaphragm therein is bent backwards at an angle of less than 90.degree. with the motor shaft and carries curved guide vanes. The guide vanes catch the air, which is provided with a rotary motion by the air moving means, and redirects the air in an axial direction parallel to the axis of the casing.
Charles H. Sparklin, in U.S. Pat. No. 2,438,133, owned by the assignee hereof, shows a split cylindrical housing for suction cleaners which is generally oval in transverse cross section and houses a two-stage fan, each portion of which is provided with curved blades directing the air outwardly towards the walls of the housing.
In U.S. Pat. No. 2,726,033 of Robert E. Sheahan, a fan and motor unit assembly is disclosed having a two-stage vacuum cleaner fan.
Ralph D. J. Griffiths, in U.S. Pat. No. 3,246,359, shows a compact vacuum cleaner with storage means having a rectangular cross section housing which, in turn, defines a plurality of different forms of fan housings.
In U.S. Pat. No. 3,334,370 Wilton E. Boyd discloses a lightweight portable vacuum cleaner having a single stage fan mounted in a generally cylindrical housing.
Robert C. Greenheck, in U.S. Pat. No. 3,425,621, shows an inline centrifugal fan with door wherein the fan is mounted within a relatively large outer parallelepiped housing.
U.S. Pat. No. 3,687,568 of Olin L. Looker; U.S. Pat. No. 3,759,627 of Arnold H. Ehlinger, and U.S. Pat. No. 3,829,250 of Wilfred J. Samson, Jr. are similar to Greenheck in teaching the use of generally parallelepiped outer housings in which the air moving fan is installed.
U.S. Pat. No. 3,791,772 of Keimpe K. Keimpema et al discloses a vacuum cleaner fan assembly comprising a two-stage fan having a diffuser housing defining a ring of guide blades forming a radial diffuser for bypassing air in an axial direction.
As illustrated in FIG. 13 of the drawing herein, where a cylindrical fan impeller is mounted in a square housing, a predetermined air moving performance is obtained as illustrated in curve B. Where such a cylindrical fan impeller is mounted in a cylindrical housing, a somewhat lower air moving performance is obtained, as illustrated by curve C.